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1st gen DTRL and LED projectors

Discussion in 'Lighting' started by shortround13, Feb 15, 2023.

  1. Feb 15, 2023 at 8:39 AM
    #1
    shortround13

    shortround13 [OP] Well-Known Member

    Joined:
    Dec 10, 2014
    Member:
    #144048
    Messages:
    202
    Gender:
    Male
    Sacramento
    Vehicle:
    04 DblCab TRD 4x4
    First, to save a bunch of reading, has anybody successfully disabled the DTRL on a 1st gen with projector retrofits?

    Why am I asking? Well, I followed this mod:
    https://www.tacomaworld.com/threads/disable-drls.70500/#post-1332343
    cut the white-green wire and with OEM halogens, it worked. DTRL stayed off, everything else functioned normally. Success.

    Installed LED projectors and got wonkiness. Both sides R/L would flash between high/low at differing speeds whenever the "DTRL" (parking brake released) would normally have been on. Turning the actual headlight switch to "on" stopped this, while on, but immediately reverted to the flashing if rotated to "off" until the truck was turned off.

    What I have tried:
    1. white-green wire - no (see above)
    2. white-black wire - "normal" DTRL (no flashing, appeared to be a high beam pattern)

    3. white-green AND white-black wire - same as above #2

    4. installed a resistor T-harness from TRS (Morimoto brand) - it dimmed and caused the lights to flicker

    5. removed the fuse under the hood - all headlight functions disabled, no good
    6. unplugged the DTRL main relay under the dash completely - same as #5

    From my more electrically inclined members, what do you see as options? What I think is happening is that on a halogen bulb, removing the white-green wire is dropping the voltage in the system enough that you don't get any light, thus in essence disabling the DTRL, but with the LED projector, there's enough voltage still making its way thru the overly complicated system and dimmer switch to activate the lights, and for some reason it doesn't like that wire being removed and gives me the flashing between high/low.

    My dummy brain sees two more potential options?
    1. With 1st gen DTRL operation, it does not get triggered on UNTIL the parking brake gets released, and once it is released they stay active until the ignition gets shut off. So, I could potentially mess with the parking brake switch and make the truck think the parking brake is always on? But, that would come with the side effect of always having the "brake" illuminated on the dash (unless I pulled the bulb, which I'd rather not do)

    2. maybe, just maybe, if I remove the yellow wire @ pin #9, this is where it all begins. It receives a signal from the generator when the engine is started and starts the magic inside of the DTRL main relay. Only problem, for whatever reason, I cannot get the dang pin to release to pull the terminal out of the connector. All of its neighbors, sure! but the one I want, nope. So, damage free test is not an option, and I am very hesitant to cut it because it'd be a major pain to repair....

    The other thing, and for the life of me I can't find where now, I remember reading a TSB that mentioned accessing the DTRL #4 relay and removing a wire from it in addition to a wire from the main relay, but, not sure that would make a difference? #4 relay is way up tight under the glove box and not easy to access either

    Any electrical guru's with insight? I'm tempted to call Toyota and see if they can do it for me....
     

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